Apparatus for cleaning seal edge regions of cathode ray tube panels

ABSTRACT

An apparatus is provided for cleaning extraneous coating material from the seal edge region of a cathode ray tube face panel. The coated panel is horizontally positioned with the sidewall edge thereof oriented in a downward direction over a container of solvent. A shielding member is spatially positioned to protect the viewing area of the panel from subsequent spurious splashings of the solvent. The surface of the solvent is contacted with mesh-like member to break the surface tension thereof in a turbulent-free manner, whereupon, the seal edge is immediately immersed in the solvent to loosen the extraneous edge-oriented coating. The interior of the inverted panel is vented to facilitate the rise of the solvent to the desired level of the interior of the panel sidewall. The panel edge is thence removed and rinsed to remove the loosened coating from the edge region.

nited States atent [191 Dapolito et al.

[4 1 Mar. 25, 1975 [75] Inventors: Joseph ,1. Dapolito, Lyons; Gustav A.Stachelhaus, Seneca Falls, both of NY.

[73] Assignee: GTE Sylvania Incorporated,

Stamford, Conn.

[22] Filed: Mar. 21, 1973 [21] Appl. No.: 343,391

[52] US. Cl 134/140, l17/8.5, 118/56,

134/23, 134/32, 134/152, 134/201 [51] Int. Cl B08b 3/08 [58] Field ofSearch 134/32, 23, 26, 39, 137,

134/152,166 R, 201, 140; 117/8, 33.5 C, 33.5 CM, 102 R, 8.5; 118/567/1973 Pekosh 1.34/166 R X 9/1973 Pekosh 1l7/33.5 C

Primary E.\'aminer-S. Leon Bashore Assistant E.\'aminer-Richard V.Fisher Attorney, Agent, or Firm-Norman J. OMallcy; Frederick H. Rinn;Cyril A. Krenzcr [57] ABSTRACT An apparatus is provided for cleaningextraneous coating material from the seal edge region of a cathode raytube face panel. The coated panel is horizontally positioned with thesidewall edge thereof oriented in a downward direction over a containerof solvent. A shielding member is spatially positioned to protect theviewing area of the panel from subsequent spurious splashings of thesolvent. The surface of the solvent is contacted with mesh-like memberto break the surface tension thereof in a turbulent-free manner,whereupon, the seal edge is immediately immersed in the solvent toloosen the extraneous edge-oriented coating. The interior of theinverted panel is vented to facilitate the rise of the solvent to thedesired level of the interior of the panel sidewall. The panel edge isthence removed and rinsed to remove the loosened coating from the edgeregion.

6 Claims, 8 Drawing Figures PATENIED 3.873.365 SHEET 1 [15 g APPARATUSFOR CLEANING SEAL EDGE REGIONS OF CATHODE RAY TUBE PANELS BACKGROUND OFTHE INVENTION This invention relates to color cathode ray tubes and moreparticularly to an apparatus for cleaning the edge region of tube facepanels during tube manufacturing.

Color cathode ray tubes, such as those employed in televisionapplications often have patterned multiplex screen structures comprisingreflective groups of related phosphor elements whereof the interstitialspacing between adjacent pattern elements is covered by an opaquelight-absorbing material. Specifically, to improve contrast eachphosphor element is defined by an opaque encompassment, of for examplegraphite, which collectively comprise a foraminous pattern in the formof a windowed webbing having an array of substantially opaque-connectedinterstices. While such web-like structures have been fabricated eitherbefore or after screening of the phosphor elements, it has been foundmost expeditious to form the opaque windowdefining-webbing on the panelbefore deposition of the phosphors. By one screen forming procedure, apattern of clear polymerized polyvinyl alcohol pattern elements is lightdisposed on the. panel on those areas subsequently to be windows in theopaque webbing, by photo exposure through a related apertured maskmember. After development, the resultant island-like polymerized patternelements are surrounded by bare interstitial areas of glass. The opaquegraphite coating is then applied to completely overcoat the interior ofthe panel covering the clear pattern elements and the adjacent bareinterstitial glass areas. Next, an oxidizing agent is applied tocompletely degrade the polymerized window pattern elements therebyloosening the superjacent opaque coating thereon, whereupon thematerials so loosened are removed by a subsequent water developmentstep. Thus, there is formed an opaque interstitial web of graphitematerial having multitudinous windows defined as bare glass areas of asize related to the apertures in the pattern mask members. Since thegraphite has been previously disposed over the whole of the interior ofthe panel, it is also residual in the sealing edge region of the panelsidewall. It is essential that this extraneous graphite material beremoved from the region of the panel sealing edge to facilitatesubsequent hermetic bonding of the panel to the funnel portion of theenvelope assembly. Usually, the removal of the graphite from the sealedge region is accomplished either before the oxidizing agent is appliedto degrade the polymerized window pattern or immediately following theensuing development step. Regardless of when this necessitous cleaningoperation is performed, it is both a painstaking and time-consumingprocess. One procedure commonly used is to hand wipe the seal edge withsponges and an abrasive rubber block. A disadvantage of this handoperation is evidenced when the sponges and blocks become increasinglycontaminated with graphite after the treatment of several panels, acondition which hinders efficient cleaning of the panel. In addition,any deviation in the hand cleaning procedures causes synchronizationdifficulties with other facets of the related machine-paced tubemanufacturing operation.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the invention toreduce the afore- LII mentioned disadvantages by providing an efficientapparatus for cleaning the sealing edge region of cathode ray tubepanels. Another object is to provide a panel cleaning apparatus that iscapable of synchronization into the machine-paced tube manufacturingoperation.

These and other objects and advantages are achieved in one aspect of theinvention by the provision of an apparatus for cleaning extraneouscoating from the seal edge region of a CRT face panel. The coated panelis located in a horizontal position with the sidewall edge oriented in adownward direction over a container of liquid solvent solution. Ashielding member contoured of a shape similar to that of the panel ispositioned to protect the coating disposed on the viewing area, andsidewall portion contiguous thereto, from subsequent possible spurioussplashings of the related solvent. The shielding member is spatiallyrelated to both the panel and the solvent. The surface of the solvent iscontacted with means for breaking the surface tension thereof in aturbulent-free manner; whereupon, the sealing edge of the panel isimmediately immersed into the solvent to loosen the bonding of thecoating material contacted. The interior of the panel is vented toatmospheric pressure to facilitate the rise of the solvent to thedesired level on the interior coated surface of the panel sidewall. Thepanel edge region is thence removed from the solvent, the withdrawalbeing consummated in a manner to minimize turbulence of the solvent. Thepanel is thence rinsed to remove the loosened coating from the edgeregion.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded isometric viewillustrating constructional details of the cleaning apparatus;

FIGS. 20, 2b, and 2c are sectional views of the assembled apparatustaken substantially along the line 2-2 of FIG. 1 showing severaloperational aspects of the apparatus;

FIG. 3 is an isometric view of a panel positioning block;

FIG. 4 is an enlarged sectional view showing a portion of the panelpositioning block as taken along the line 4-4 of FIG. 3;

FIG. 5 is an enlarged sectional showing the seating of the panel edge inthe V of the positioning block as illustrated in FIGS. 2b and 2c; and

FIG. 6 is a sectional view illustrating the panel rinsing operationfollowing panel cleaning in the apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT For a better understanding ofthe present invention, together with other and further objects,advantages and capabilities thereof, reference is made to the followingspecification and appended claims in connection with the aforedescribeddrawings.

With particular reference to FIG. 1, there is shown an explodedisometric view of the constructional aspects of the panel cleaningapparatus 11. In conjunction therewith, FIGS. 20, 2b and 2c delineatethe relationship of the several components comprising the apparatusassembly and the solvent solution 12 contained therein.

An open-top liquid container or tank 13, horizontally oriented andaffixally located on a base member 15, is formed of stainless steel or achemically resistent and substantially rigid plastic material such asP.V.C. The

container is constructed to hold a quantity of the liquid solventsolution 12 at a predetermined level as evidenced by the outflow orifice17. One embodiment of the open top container is shaped as a continuouschannel 19 forming a ring-like structure whereof the inner sidewall 21defines a substantially vertically oriented centralized tubular-likestructure 23, the opening providing venting means, the function of whichwill be described later in this specification.

A frame member 27 is constructed of a perimetrical portion 29 with aplurality of spatially related lateral structural elements 31 joined toan annular member 33. This annular member is formed to accommodatevertical movement of the frame 27 relative to the tubular vent 23. Theframe is supported by a plurality of spaced apart supportive means 37,each comprising an edgeoriented guide bracket 39 with a bore 41 thereinto slidably accommodate a guide rod 43 extended therethrough. Each ofthe respective guide rods is positioned by a holding means 45 which isattached to the base member exteriorly of the container 13. A resilientelement such as a helical spring 47, encompassing each guide rod 43,provides the support for each of the frame guide brackets 39 therebyeffecting suspension of the frame member 27 within the container in amanner to facilitate vertical reciprocating movement of the frametherein.

At least one multi-apertured or mesh-like member 51 is shaped andlaterally positioned on and attached to the frame member in a manner tobe vertically movable with the frame. The mesh member, which is formed,for example, of stainless steelyhas a cut out portion 53 to facilitatemovement thereof relative to the tubular vent 23. This mesh functions asa means for expeditiously breaking the surface tension of the solvent 12in the container 13 during operation of the apparatus. Positioned atopthe mesh member are a plurality of panel positioning blocks 55 in spacedapart relationship. These blocks, being made of a material such asnylon, are affixed to the structural elements of the frame member 27 bybolt means 57 extended through suitable holes 58 in the blocks and therelated mesh member 51 thereby also effecting attachment of the mesh tothe frame. Additionally referring to FIGS. 3, 4, and 5, each of theblocks 55 has at least one locating V configuration 59 formed therein toaccommodate portions of the sealing edge 63 of the face panel 65 in alimited contact manner, the perimetrical sealing edge of the panel beingpositioned within the V to make limited contact with each leg a and bthereof. Such limited contact is important in promoting efficient arealsolvent treatment for effecting removal of the extraneous coating fromthe edge region of the panel. To further enhance limited contact, thesealing edge 66 of the locating V is beveled or chamfered along bothedges 67.

A shielding member 71, of a material such as epoxy, is positioned withinthe viewing panel 65 to protect the coating, not shown, disposed on theinterior surface of the viewing area 73 thereof and on the sidewallportion 75 contiguous thereto. This protective shield, while beingsmaller than the interior dimensions of the panel, is contoured of ashape similar to that of the interior surface of the panel, and ispositioned in a manner spatially related to the interior surface of thepanel and the adjacent solvent solution 12 in the container 13. Theshielding member 71 is spaced above and substantially central to theframe member 27 and suitably affixed thereto by a plurality ofsupportive brackets 79. Therefore, during operation of the apparatus,the shield and the frame member are moved vertically and simultaneouslyin a constant spatial relationship, whereof the shielding member isalways above the level of the solvent solution 12. The tubular ventconstruction 23 is oriented to open beneath the shielding member.

The tube face panel 65 being of skirted construction has a surroundingsidewall portion perimetrically extending from the periphery of theviewing area 73. The panel is predeterminately positioned in ahorizontal inverted manner with the sidewall sealing edge 63 oriented ina downward direction over the shielding member 71. This panelpositioning is accomplished. for example, by panel supportive means 81formed as a vacuum holding arrangement functioning in conjunction withthe outer surface of the panel. Such panel supportive means is adaptiveto usage for accurately positioning the panel and sequentially movingthe same through a number of related stations in an automatedmanufacturing operation.

The container 13 and associated frame member 27 are positionally relatedto base member 15 which, in turn, is supported by apparatus supportmeans 85.

For the apparatus to function, it is necessary to effect relativemovement between the panel and the solution container to facilitateimmersion of the edge-related area of the panel in the solvent solution.The panel edge immersion can be accomplished in either of twoprocedures. For example, as shown in FIGS. 2a, 2b, and 2c, the panel 65is located by support means 81 in a constant position, and the apparatussupport means 85 is moved vertically by a controlled reciprocatingmovement means, not shown, to enable the liquid solution 12 to makecontact with the stationary sealing edge region of the panel 65. Suchvertical reciprocation is achieved by conventional fluid or mechanicalmeans readily conjunctive with the apparatus support means. Anotherprocedure for effecting the relative movement between the panel and thesolvent is to maintain the solvent container 13 at a constant level;whereupon, the panel support means 81 is moved in a predeterminedvertical manner by controlled reciprocating means, not shown, to enablethe panel edge region to be immersed in and removed from the solvent.Such movement can be readily understood by reference to the figures.

Reference is directed to FIGS. 2a, 2b, and 20 for further explanation ofthe apparatus for cleaning the coating from substantially the sealingedge region of a cathode ray tube face panel. With particular referenceto FIG. 2a, a cathode ray tube face panel 65 is, for example, at thatstage of screen fabrication wherein the opaque coating material, such asgraphite and a binder, has been disposed over the polymerized PVApattern of window elements. The graphite coating material, not shown,covers the whole of the interior of the panel including the sealing edgeregion from which it is removed by the invention. The panel 65 is placedand held by supportive means 81 in a horizontal position with thesidewall edge 63 oriented in a downward direction over an open-topcontainer 13 having therein a controlled and predetermined level ofliquid solvent solution 12.

The solvent is substantially a weak acidic solution to soften thebonding of the graphite associated binder. For example an aqueoussolution comprising about one percent by volume of hydrofluoric acid andone percent by volume of sulfuric acid has been found satisfactory forthe process.

Immediately beneath the panel, the contoured shielding member 71 of theapparatus is spatially and centrally oriented to subsequently protectthe graphite coating disposed on the panel viewing area 73 from anyspurious splashings of the solvent material. In FIG. 2b, the solventcontainer is raised toward the panel to effect seating contact therewithin the appropriate V configurations 59 formed in the panel positioningblocks 55. The operation continues from FIGS. 2b to wherein thecontainer is further raised, to the full of the upward movement. Asdiscrete and limited areas of the panel edge 63 are pressured on thepositioning blocks 55, the helical springs 47 of the frame supportivemeans are compressed and the frame member 27, which is initially abovethe solvent level at the beginning of the cycle, is lowered into thesolvent 12 carrying with it the mesh-like member 51. As the mesh makesimmersive contact with the solvent, it breaks the surface tensionthereof in a turbulent-free manner, and as the panel edge is immersedimmediately thereafter, there is a minimum of surface turbulence whenthe sealing region enters thereinto. The interior of the panel is ventedto ambient atmospheric pressure by vent construction 23 whichfacilitates the rise of the solvent to the desired level on the interiorcoated surface of the sidewall.

After immersing the panel edge region for a time period in the order oftwo to four seconds, the reverse of the process is initiated forremoving the panel from the solvent. As the container 13 is lowered, thepanel emerges from the solvent before the mesh and associated framemember, whereupon the solvent liquid drains from the panel through themesh member. The panel positioning blocks and the adjacent mesh breakthe surface tension that holds the solvent solution to the panel sealingedge, thus the mesh prevents the formation of bubbles and resultantsurface turbulence as the apparatus returns to the starting position.Minimizing turbulence associated with disruption of the surface tensionof the solvent immediately associated with immersion and egression ofthe panel edge therewith reduces the prevalence of minute splashing ofthe interior of the panel. The solvent reacts on the bonding of thegraphite coating, loosening but not removing it from the seal edgeregion, therefore, the solvent does not become unduly contaminated withgraphite material.

After the coated panel is subjected to treatment in the solution, it ismoved to an adjacent station 89, as indicated in FIG. 6, whereupon thepanel is rinsed with water supplied by flow means 91. This rinsing stepremoves the loosened extraneous graphite coating from the region of theseal edge 63. Thus, the edge of each panel is expeditiously cleaned in arepetitive uniform manner.

While there has been shown and described what are at present consideredthe preferred embodiments of the invention, it will be obvious to thoseskilled in the art that various changes and modifications may be madetherein without departing from the scope of the invention as defined bythe appended claims.

What is claimed is:

1. In relation to a cathode ray tube panel formed of a viewing area witha perimetrical sidewall terminated by a sealing edge therearound andhaving a coating disposed over the interior surface of the panel, anapparatus for cleaning the coating from substantially the sealing edgeregion of said panel sidewall, said apparatus comprising:

panel supportive means for locating said panel in a horizontal positionwith said sidewall edge oriented in a downward direction;

an open-top container oriented beneath said panel supportive means andadapted to contain a quantity of a solvent liquid at a predeterminedlevel therein, said container including at least one sub stantiallyvertically and centrally oriented tubularlike venting means positionedto extend above said liquid level therein;

a frame member formed for suspension within the confines of saidcontainer in a manner to effect predetermined and restricted verticalreciprocating movement therein, said frame being constructed of aperimetrical portion having a plurality of spatially related lateralstructural elements connective therewith, said frame member having saidpanel supportive means associated therewith;

supportive means for said frame formed of guided resilient elementslocated externally of the interior of said container;

a mesh-like member positioned laterally on said frame member in a mannerto be vertically movable therewith, said mesh-like member being orientedbeneath said panel supportive means;

a plurality of panel positioning means oriented atop said meshlikemember in a spaced-apart relationship and affixed to said frame memberin positions to make contact with said panel;

a shielding member having an exterior contour related to that effectedby the interior surface of said panel, said shielding member beingspaced above and affixed to said frame member at a locationsubstantially central thereto in a manner to be vertically movabletherewith in the region above the level of said liquid, said ventingmeans opening beneath said shielding member;

apparatus support means associated with said container; and

means for effecting relative movement between said panel and associatedmesh-like member with said container to facilitate immersion andwithdrawal of said mesh-like member and the edge-related area of saidpanel into and out of said liquid solvent solution.

2. The panel cleaning apparatus according to claim 1 wherein said panelpositioning means are discretely formed blocks having provisions thereinto make contact with selected portions of substantially the sealing edgeof said panel to properly position the edgerelated area thereof forcleaning.

3. In the panel cleaning apparatus according to claim 2, wherein each ofsaid panel positioning blocks has at least one locating V formed thereinto accommodate the sealing edge of the panel in a limited contactmanner, the perimetrical sealing edge of said panel being positionedwithin the V to make contact with each leg thereof.

4. In the panel cleaning apparatus according to claim I, wherein saidopen-top container is shaped as a continuous liquid-containing channelforming a ring-like structure whereof the inner sidewall defines asubstantially vertically oriented centralized tubular-like strucframehaving a plurality of edge-oriented guide brackets each with a boretherethrough to match a respective guide rod thereby facilitatingreciprocating movement of said frame.

6. In the panel cleaning apparatus according to claim 1, whereinmovement between said panel and said container is effected by avertically reciprocating move- "ment means predeterminately raising andlowering said container to enable the liquid therein to make contactwith the sealing edge region of said panel.

1. In relation to a cathode ray tube panel formed of a viewing area witha perimetrical sidewall terminated by a sealing edge therearound andhaving a coating disposed over the interior surface of the panel, anapparatus for cleaning the coating from substantially the sealing edgeregion of said panel sidewall, said apparatus comprising: panelsupportive means for locating said panel in a horizontal position withsaid sidewall edge oriented in a downward direction; an open-topcontainer oriented beneath said panel supportive means and adapted tocontain a quantity of a solvent liquid at a predetermined level therein,said container including at least one substantially vertically andcentrally oriented tubular-like venting means positioned to extend abovesaid liquid level therein; a frame member formed for suspension withinthe confines of said container in a manner to effect predetermined andrestricted vertical reciprocating movement therein, said frame beingconstructed of a perimetrical portion having a plurality of spatiallyrelated lateral structural elements connective therewith, said framemember having said panel supportive means associated therewith;supportive means for said frame formed of guided resilient elementslocated externally of the interior of said container; a mesh-like memberpositioned laterally on said frame member in a manner to be verticallymovable therewith, said mesh-like member being oriented beneath saidpanel supportive means; a plurality of panel positioning means orientedatop said meshlike member in a spaced-apart relationship and affixed tosaid frame member in positions to make contact with said panel; ashielding member having an exterior contour related to that effected bythe interior surface of said panel, said shielding member being spacedabove and affixed to said frame member at a location substantiallycentral thereto in a manner to be vertically movable therewith in theregion above the level of said liquid, said venting means openingbeneath said shielding member; apparatus support means associated withsaid container; and means for effecting relative movement between saidpanel and associated mesh-like member with said container to facilitateimmersion and withdrawal of said mesh-like member and the edgerelatedarea of said panel into and out of said liquid solvent solution.
 2. Thepanel cleaning apparatus according to claim 1 wherein said panelpositioning means are discretely formed blocks having provisions thereinto make contact with selected portions of substantially the sealing edgeof said panel to properly position the edge-related area thereof forcleaning.
 3. In the panel cleaning apparatus according to claim 2,wherein each of said panel positioning blocks has at least one locatingV formed therein to accommodate the sealing edge of the panel in alimited contact manner, the perimetrical sealing edge of said panelbeing positioned within the V to make contact with each leg thereof. 4.In the panel cleaning apparatus according to claim 1, wherein saidopen-top container is shaped as a continuous liquid-containing channelforming a ring-like structure whereof the inner sidewall defines asubstantially vertically oriented centralized tubular-like structure theopening of which provides said venting means, said frame and saidmesh-like member each having provisions therein to accommodate saidtubular structure therethrough and provide for vertical movement of saidframe and mesh relative to said tubular structure, said shielding memberbeing spatially oriented above the opening in said tubular structure. 5.In the panel cleaning apparatus according to claim 1, wherein thesupportive means for said frame comprise a plurality of verticallypositioned helical springs each having a fixed vertical guide rodtherein, said frame having a plurality of edge-oriented guide bracketseach with a bore therethrough to match a respective guide rod therebyfacilitating reciprocating movement of said frame.
 6. In the panelcleaning apparatus according to claim 1, wherein movement between saidpanel and said container is effected by a vertically reciprocatingmovement means predeterminately raising and lowering said container toenable the liquid therein to make contact with the sealing edge regionof said panel.